In cucumbers, dull fruit (D) is dominant over glossy fruit (d), orange fruit (R) is dominant over cream fruit (r), and bitter cotyledons (B) are dominant over non-bitter cotyledons (b). The three characters are encoded by genes located on different pairs of chromosomes. A plant homozygous for dull, orange fruit and bitter cotyledons is crossed with a plant that has glossy, cream fruit and non-bitter cotyledons. The F1 are intercrossed to produce the F2 .

a. Give the phenotypes and their expected proportions in the F2 .
b. An F1 plant is crossed with a plant that has glossy, cream fruit and nonbitter cotyledons. Give the phenotypes and expected proportions among the progeny of this cross.

a)

b)

Explanation:

The three genes are located on different chromosomes.

a) A plant homozygous for dull, orange fruit and bitter cotyledons (DDRRBB) is crossed with a plant that has glossy, cream fruit and non-bitter cotyledons (ddrrbb).

The F1  (DdRrBb) are intercrossed (DdRrBb X DdRrBb) to produce the F2.

The genes are on different chromosomes so they assort independently during meiosis. If you do a Punnett Square of this cross, you will see that the phenotypic frequencies are:

b) An F1 plant  (DdRrBb) is crossed with a plant that has glossy, cream fruit and nonbitter cotyledons (ddrrbb).

In this case, the homozygous recessive plant can only produce 1 type of gamete (drb). The phenotype of the offspring will depend entirely on the type of gametes the F1 plant produced, of which there are 8 types:

DRB, DRb, DrB, Drb, dRB, dRb, drB, drb.

As the genes are independent, all of these gametes have the same probability of being produced: 1/8.

The phenotypes and their proportions will be:

surface mining destroys mountain tops, landscapes, forests and wildlife habitats. on top of that, it leads to soil erosion and destruction of agricultural land. the landscape changes can also disrupt river channels and streams, which leads to flooding. which, can destroy plant life and other animals as well.

explanation: